Phys 2.5 Hearing PDF
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This document discusses human hearing, including the anatomy of the ear, how sound waves are transmitted, hearing acuity, and potential hearing damage. It includes questions and activities, and references limits of hearing in humans and animals.
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## 2.5 Hearing We know that sound waves are vibrations that propagate through air and all material mediums, but how do we get to hear these waves? The ear is the **"detector" of angels**, it is built in such a way that it catches every sound wave. The construction of the ear is shown in the figure...
## 2.5 Hearing We know that sound waves are vibrations that propagate through air and all material mediums, but how do we get to hear these waves? The ear is the **"detector" of angels**, it is built in such a way that it catches every sound wave. The construction of the ear is shown in the figure below. * The vibrations pass through the **ear canal**. * The one that vibrates "hits" on the **ear drum** so that **it also starts to vibrate**. * The **drum** pushes **three small bones** causing them to vibrate as well. * The smallest bone conducts the vibrations of the **ear drum** to the **cochlea**, which is a twisted tube filled with fluid. * The vibrations propagate through the fluid, exciting the **nerve cells** inside the **cochlea**. These cells send electrical signals to the brain via nerves, making it possible to perceive sound. **1. Arrange the following words according to the way sound wave vibrations are transmitted from the ear to the brain.** * snail * the ear canal * three small bones * the ear drum * cranial nerves * nerves **Hearing acuity** Man at a young age has keen hearing. Young people can hear very faint sounds, but they can also pick up very high-pitched sounds. With age, a person gradually loses the ability to hear exactly weak sounds and those with a high pitch. A signal generator and a loudspeaker are used to determine the highest pitch we can hear. **The signal generator can produce sounds with different frequencies.** **Activity 2.5** **Hearing control** The teacher will use a signal generator to produce sounds with different frequencies. **Determine which is the highest and lowest frequency you hear.** ## Limits of hearing Most people cannot hear sounds with a frequency lower than 120 Hz and higher than 20,000 Hz. These limits are for youth (those under the age of 20). As you get older, you lose your hearing. Around the age of 50, a person cannot hear sounds with a frequency above 15,000 Hz. Sounds with a frequency above 20,000 Hz are beyond the limits of human hearing, which is why they are called ultrasound. Only animals can hear ultrasound with free ears. For example, bats use ultrasound to navigate their surroundings. They emit high-frequency signals and listen to the waves reflected by objects. In general, when a sound wave hits the surface of a large obstacle, it is reflected. If the reflected sound wave is discernible in our ears, an echo is obtained. **Ultrasound echoes (cko) are used in medicine, fishing, the last study of the sea, etc.** **The bat can determine its distance from objects by listening to reflected ultrasound.** **Image of a fetus, obtained through ultrasound.** **Questions and assignments** **2. Which of the following frequencies is expected to be heard by a young person?** * 500 Hz * 6 000 Hz * 25 000 Hz * 15 Hz * 15 000 Hz In everyday life, we encounter many annoying sounds that we don't want to hear. These unwanted sounds are called noise. Loud sounds can damage the ears. Listening to music with headphones can be harmful if the volume is too high. Special laws are often drafted to protect workers who work in noisy environments. **In order not to become deaf, workers must wear ear protection against noise.** **Keep the volume low, otherwise you may damage your hearing.** **Questions and assignments** **3. Mention some professions, where workers necessarily face noisy environments.** **Briefing** Our ears convert sound waves into nerve signals, which go to the brain. * Young people can usually hear sounds whose frequency ranges between 20 Hz and 20 000 Hz. * Loud sounds can damage your hearing. * Loud sounds can damage your ear. **The sound** The image is of an ear and a speaker. The ear has an arrow pointing to the ear canal and ear drum. There are three small bones that connect the ear drum to the cochlea. There is a diagram of the human ear.